Gas analyzer

ABSTRACT

A gas analyzer comprising a sample cell adapted to receive a gas to be analyzed and a reference cell for receiving a gas to be compared, both of which are disposed between a source of light and a detector, and clamping members for clamping together a protective casing and a common cell base for support of said sample and reference cells. Other advantages and details of the arrangement will be made clear.

United States Patent Shimazaki et al.

[ Jan. 29, 1974 Filed:

GAS ANALYZER Inventors: Toshio Shimazaki; Fumio Tanei;

Yoshio Yanagida, all of Kyoto, Japan Assignee: Horiba Ltd., Kyoto-Fu,Japan Aug. 31, 1971 Appl. No.: 176,660

US. Cl. 356/246 Int. Cl. G01n l/10 Field of Search 356/51, 246, 244;250/4354 References Cited UNITED STATES PATENTS Ishimaru 356/2462,744,440 5/1956 Robertson et al. 356/246 Primary Examiner-William L.Sikes Attorney, Agent, or Firm-Hall and Houghton ABSTRACT A gas analyzercomprising a sample cell adapted to receive a gas to be analyzed and areference cell for receiving a gas to be compared, both of which aredisposed between a source of light and a detector, and clamping membersfor clamping together a protective casing and a common cell base forsupport of said sample and reference cells. Other advantages and detailsof the arrangement will be made clear.

5 Claims, 3 Drawing Figures PATENTEU JAN 2 9 i974 SHEU 2 Bf 2 INVENTOKSGAS ANALYZER BACKGROUND OF THE INVENTION 1. Field of the Invention Thepresent invention relates to arrangements of the gas receiving means,piping construction and assembling construction in infrared gasanalyzers, ultraviolet gas analyzers, colorimetric analyzers and othervarious gas analyzers.

2. Description of the Prior Art Generally, it is necessary to change thelength of the sample receiving means, i.e., gas receiving cell in gasanalyzers according to the amount and concentration of a sample gas andto clean said cell after analysis. Therefore, said cell, protectivecasing for the cell, gas piping, etc. have to be attached and detachedeach time gas analysis is conducted. Heretofore, the means for fixingsaid cell and protective casing together, the joints between the celland gas piping and between the gas piping and protective casing, etc.have been separate from and independent of each other and thus the jointconstructions are very complex. As a result, the attachment anddetachment of such parts take much trouble.

SUMMARY OF THE INVENTION According to the present invention, a samplecell for receiving a gas to be analized is of a double pipe constructionand a gas piping for said sample cell is placed in the cell. The samplecell and a reference cell for receiving a gas to be compared areretained'by a common cell base, and metal fixtures for said cell baseand protective casing are utilized to enable gas introducing anddischarging pipes to be attached and detached from outside theprotective casing. This arrangement makes it possible to eliminate thepresence of the gas piping for sample cell from within the analyzingsystem, which elimination, in turn, makes it possible to simplify theconstruction of the analyzing system, reduce the size thereof, simplifythe disassembly and assembly of the analyzing system and facilitate theattachment and detachment of the gas piping, i.e., gas introducing anddischarging pipes.

DESCRIPTION OF THE DRAWINGS In the accompanying drawings illustrating apreferred embodiment of the invention:

FIG. 1 is a schematic view of a double light path type infrared gasanalyzer;

FIG. 2 is a side view in longitudinal section of cell means which is theprincipal portion of the present invention, with sample gas introducingand discharging regions shown in front view; and

FIG. 3 is a cross-section taken along the line III-III of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION The outline of a double light pathtype infrared gas analyzer will be. given with reference to FIG. 1. Thedifference between infrared energies emitted from light sources 1 and 2and transmitted through a sample cell 3 and a reference cell 4,respectively, is selectively absorbed by a detector 5 and the detectedenergy difference is derived as a pressure difference between thechambers 6 and 7 of the detector and is then converted into an electricsignal by a capacitor microphone 8, thereby detecting the concentrationof the sample gas. Further, in order to facilitate the conversion intoelectric signals at the detector, the light paths are periodicallyinterrupted to provide an a.c. waveform. The numeral l0 denotes anamplifier.

The present invention is concerned with the abovementioned gas analyzer,and the gist of the invention is directed particularly to the cellconstruction, gas piping construction and assembling construction. Thesearrangements will now be described with reference to FIGS. 2 and 3.

The sample cell 3 includes an inner pipe 11 and an outer pipe 12hermetically secured at each end to the inner pipe 11 in spacedencircling relationship by means of a sleeve 13 and a ring 14. Thisconstruction results in the formation of an annular clearance passageway15 between the inner and outer pipes ll, 12. A communication port 16 isprovided in the end portion of the inner pipe 11 and thereby establishescommunication between the formed clearance passageway 15 and inner pipe11. The inner pipe 11 is of a length greater than the outer pipe 12 and,as illustrated, extends beyond the confines of the outer pipe 12 formingan upper extension and a lower extension with respect thereto. A gasinlet 17 is provided in the lower extension of the inner pipe 11. Theend of the outer pipe 12 adjacent the lower extension of the inner pipe11 having the gas inlet 17 is provided with a gas outlet 18. In short,the purpose of this construction is to provide gas inlet and outlet 17and 18 in the inner and outer pipes l l and 12, respectively, at thesame end of the sample cell 3 so that a sample gas which enters thesample cell 3 through the gas inlet 17 may be passed from the inner pipe11 through the communication port 16 into the formed clearancepassageway 15 and then pass from the cell 3 through the outlet 18 at thesame end of the cell.

The end portion of the sample cell 3 on the end provided with said inletand outlet 17 and 18 is hermetically fitted in a cell receiver 21 bymeans of 0-ring packings l9 and 20. The cell receiver 21, as shown inFIG. 3, is provided with communication holes 22 and 23 communicatingwith the inlet and outlet 17 and I8 of the sample cell 3, respectively.The cell receiver 21, as shown in FIG. 3 also, is suitably fixed to acell base 24 provided with gas and introducing and discharging holes 25and 26 communicating with the communication holes 22 and 23 of the cellreceiver 21, respectively. The junctions between the communication holes22, 23 and the gas introducing and discharging holes 25, 26 are providedwith O-ring packings 27, 28, respectively, which assist in hermeticallyfixing them together.

As shown in FIG. 3, the gas introducing and discharging holes 25 and 26extend in the cell base in opposite directions, the front end thereofbeing opened in a di rection perpendicular to the gas introducing anddischarging holes, and the openings are internally threaded to providethreaded holes 29 and 30. Metal fixtures 32 and 33 are screwed into saidthreaded holes 29 and 30, respectively.

The metal fixtures'32 and 33 serve to assemble a protective casing 31 tothe cell base 24 and also to connect the sample gas introducing anddischarging pipes 34 and 35 to the gas introducing and discharging holes25 and 24 in the cell base, respectively.

The metal fixtures 32 and 33, as shown in FIG. 3, have flanges 36 and37, respectively, integrally formed around their outer peripheries. Oneof the distinct outer peripheral regions thus partitioned off from eachother by such flange is shaped square to provide nut portions 38 and 39,and the other respective regions are threaded as at 40 and 41. The metalfixtures 32 and 33 have through holes 42 and 43 partitioned by steps 46and 47, respectively. One of the sides of each step 46, 47 correspondingto the nut portion is threaded to provide threaded holes 44 and 45, intowhich gas introducing and discharging pipes 34 and 35 are screwed.Further, the other respective sides partitioned by the steps 46 and 47are formed as receiving portions 50 and 51 for seal screw sleeves 48 and49. The receiving portions 50 and 51 consist of inner reduced receivingregions 81 and 82 and enlarged receiving regions 56 and 57, said reducedreceiving regions 81 and 82 being internally threaded to provideinternal threads 52 and 53 for threaded reception of the externalthreads 54 and 55 of the seal screw sleeves 48 and 49. The seal screwsleeves 48 and 49 consist of'external threads 54 and 55 adapted forthreaded engagement with the internal threads 52 and 53 of said reducedreceiving portions 81 and 82, and portions 59 and 60 adapted to befitted in said enlarged receiving portions 56 and 57, and there arecentrally provided gas flow holes 61 and 62. At the inner ends of thegas flow holes 61 and 62, i.e., on the side where the external threads54 and 55 exist, square holes 63 and 64 are formed. Further, theportions 59 and 60 are externally provided with grooves for mounting-ring packings 65, 66 and 67, 68 thereon.

The innermost regions of the threaded holes 29 and 30' opened at theopposite ends of the cell base 24 are provided with recesses 83 and 84for installing therein filter members 69 and 70 such as of a sinteredalloy.

The filters 69 and 70 are pressed in position in the openings at the gasintroducing and discharging holes 25 and 26 by means of the seal screwsleeves 48 and 49 to remove dust contained in a sample gas and toeliminate any possibility of spread of backfire outside an analizerespecially provided with an explosion-proof capability. A filter cell 71is fitted in and secured to the sleeve 13 at the end of the sample cell3.

The reference cell 4 for receiving a reference gas is fitted in the cellreceiver 21. on the one hand and on the other hand in acell receiver 72,these receivers similarly serving also for the sample cell 3. These twocells, as shown in FIGS. 2 and 3, are fixed to the cell receivers 21 and72 by set screws 73.

The opposite ends of the cells 3, 4 and filter cell 71 are closed byplates 74, 75 and 76 formed of a lighttransmitting material such aslithium fluoride, sapphire and qualtz. In addition, in FIG. 2, thenumerals 77 and 79 denote gas filling ports for the reference and filtercells, respectively, and the numerals 78 and 80 denote gas dischargingports for the reference and filter cells, respectively. 1

In conducting gas analysis, a reference gas of given concentration isintroduced into the reference cell 4, while a sample gas to be analyzedis fed to the sample cell 3 through the introducing pipe. The sample gasis passed from the introducing pipe through the gas introducing hole 25of the cell base into the gas inlet 17 of the sample cell 3, wherefromit is passed through the inner pipe 11, through the communication port16 and then through the annular clearance passageway and into the gasoutlet 18, wherefrom it is passed through the communication port 23 ofthe cell receiver 21 and is finally discharged from the discharging pipevia the gas discharging hole 26 of the cell base 24. In this condition,infrared rays, ultraviolet rays or other rays of light are emitted toone end of each of the reference and sample cells 4 and 3 and thetransmittances, colors, etc. of the transmitted rays of light arecompared with each other for measurement.

In some cases, a suitable gas may be filled in the filter cell 71 inorder to remove the obstructive component of the gas to be analyzed. Inaddition, the principle of the gas analysis is the same as that of theconventional gas analyzer.

As has been described so far, according to the present invention, thesample cell means is in the form of a double pipe; gas inlet and outletare provided on one side; the annular clearance passageway communicateswith the gas inlet and outlet; and the annular clearance passageway,which is defined between the inner and outer pipes, communicates at theother end with the interior of the inner pipe. This arrangement enablesthe piping within the analyzing system to be assembled in the cellsection. As a result, it is possible to substantially eliminate thepresence of the piping of the sample cell from within the analyzingsystem and greatly facilitate the attachment and detachment of the cellat the time of replacement and cleaning of the cell.

Especially when the protective casing should be made explosion-proofwith a pressure resistant construction, any piping within the casingwhich naturally requires an additional space is dispensable. As theresult, the casing is compact, inexpensive and easier in handling.

Further, according to the invention, the metal fixtures for clamping theprotective casing and cell base together are each provided with a gaspassageway extending therethrough; a seal screw sleeve having a gas flowhole is screwed into each said gas passageway; and after the protectivecasing and cell base are fixed togetherby said metal fixtures, the sealscrew sleeves establish gas-tight communication between the gaspassageways in the metal fixtures and the gas introducing anddischarging holes in the cell base. This arrangement enables the cell ofdouble pipe construction to be attached and detached simultaneously withthe attachment and detachment of the casing. Therefore, the

cleaning of the cell section is simplified and facilitated.

Further, according to the invention, since the innermost regions of thethreaded holes in the cell base are provided with recesses, and filtermembers formed of a sintered alloy or the like are fitted in therecesses and secured in position by the seal screw sleeves, dust whichmay be contained in a gas to be analyzed can be removed, and in caseswhere a sample gas in the gas analyzer provided with an explosion-proofconstruction is irradiated with a heat ray such as infrared ray, spreadof any resultant flame outside the analyzer is successfully prevented.

While there have been described herein what are at present consideredpreferred embodiments of the several features of the invention, it willbe obvious to those who have engaged in development and research of gasanalyzer that modifications and changes may be made without departingfrom the principle of the invention. It is therefore to be understoodthat the exemplary embodiments thereof are illustrative and notrestrictive of the invention, the scope of which is defined in theappended claims and that all modifications that come within the meaningand range of equivalency of the claims are intended to be includedtherein.

We claim:

1. A gas analyzer comprising a reference cell for re ceiving a samplegas to be compared, a double wall sample cell for receiving a gas to beanalyzed, said sample cell including an inner pipe and an outer pipeforming a sealed annular clearance passageway therebetween through whichgas will pass, inlet means at one end of said inner pipe, outlet meansat the end of said outer pipe contiguous with the end of said inlet pipehaving the inlet means, and an opening in said inner pipe remote fromthe inlet means forming a connecting passageway between the inner pipeand an outer pipe to the formed annular clearance passageway, a commoncell receiver for receiving and supporting said two cells, a cell basefor said receiver, said base having gas introducing and dischargingopenings therein, a casing for protecting said two cells and metalfixture means for clamping said cell base and said casing together andestablish an operative communicating relationship between said gasintroducing and discharging openings of said base with said inlet meansand said outlet means of the inner and outer pipes respectively.

2. A gas analyzer in accordance with claim 1, wherein said gasintroducing openings and said gas discharging openings extend inopposite directions and each of said openings being threaded forthreaded reception of the metal fixtures having gas passageways.

3. A gas analyzer as set forth in claim 2 having seal screw sleeves,wherein the innermost region of each opening in the cell base isprovided with a recess in which a filter member formed of a sinteredalloy or the like is fitted and, after the tightening of the metalfixtures, said filter members are secured in position in the recesses bythe seal screw sleeves.

4. A gas analyzer as set forth in claim 3, wherein each of the sealscrew sleeves to be received in the asso ciated metal fixtures has athrough hole and is externally threaded at one end thereof for threadedengagement in the threaded hole in the innermost region of the receivingportion, and the end of the through hole on the threaded side terminatesin a square hole to permit the tightening of the associated seal screwsleeve from outside the associated metal fixture, and the outerperipheral region other than the threaded region is provided with anannular groove for receiving an O-ring packing therein.

5. A gas analyzer as set forth in claim 1 and having seal screw sleeves,wherein each metal fixture has a through hole in the center and a flangearound the outer periphery thereof, and one of the distinct regions thuspartitioned off from each other by the flange is internally threaded andexternally shaped square, while the other is internally formed with aportion for receiving the associated seal screw sleeve therein andexternally threaded for threaded engagement in the associated threadedhole in the cell base.

1. A gas analyzer comprising a reference cell for receiving a sample gasto be compared, a double wall sample cell for receiving a gas to beanalyzed, said sample cell including an inner pipe and an outer pipeforming a sealed annular clearance passageway therebetween through whichgas will pass, inlet means at one end of said inner pipe, outlet meansat the end of said outer pipe contiguous with the end of said inlet pipehaving the inlet means, and an opening in said inner pipe remote fromthe inlet means forming a connecting passageway between the inner pipeand an outer pipe to the formed annular clearance passageway, a commoncell receiver for receiving and supporting said two cells, a cell basefor said receiver, said base having gas introducing and dischargingopenings therein, a casing for protecting said two cells and metalfixture means for clamping said cell base and said casing together andestablish an operative communicating relationship between said gasintroducing and discharging openings of said base with said inlet meansand said outlet means of the inner and outer pipes respectively.
 2. Agas analyzer in accordance with claim 1, wherein said gas introducingopenings and said gas discharging openings extend in opposite directionsand each of said openings being threaded for threaded reception of themetal fixtures having gas passageways.
 3. A gas analyzer as set forth inclaim 2 having seal screw sleeves, wherein the innermost region of eachopening in the cell base is provided with a recess in which a filtermember formed of a sintered alloy or the like is fitted and, after thetightening of the metal fixtures, said filter members are secured inposition in the recesses by the seal screw sleeves.
 4. A gas analyzer asset forth in claim 3, wherein each of the seal screw sleeves to bereceived in the associated metal fixtures has a through hole and isexternally threaded at one end thereof for threaded engagement in thethreaded hole in the innermost region of the receiving portion, and theend of the through hole on the threaded side terminates in a square holeto permit the tightening of the associated seal screw sleeve fromoutside the associated metal fixture, and the outer peripheral regionother than the threaded region is provided with an annular groove forreceiving an 0-ring packing therein.
 5. A gas analyzer as set forth inclaim 1 and having seal screw sleeves, wherein each metal fixture has athrough hole in the center and a flange around the outer peripherythereof, and one of the distinct regions thus partitioned off from eachother by the flange is internally threaded and externally shaped square,while the other is internally formed with a portion for receiving theassociated seal screw sleeve therein and externally threaded forthreaded engagement in the associated threaded hole in the cell base.